Tire pressure.

 

It is definitely true that windows down uses much less engine power. One thing is that at faster speeds, the driver can simply close the windows partway to compensate yet still get the same circulation. That will very slightly hurt aerodynamics, but nothing like a large direct load to the engine. However, the drawback with the windows being down is that it is extremely loud at highway speeds, which is fatiguing on long drives.

I personally go with "strategic" AC use. Descending the hill from my house every day, I must normally waste energy braking (regen is not enough to maintain downhill speed), but during the summer, I run the AC in max all the way down. That makes the car very cold, so that the AC doesn't have to do much to maintain cabin temp the rest of the drive.

 

shawnb, I didn't mean for the deposit thing to be any more than a memory jog; I shouldn't have brought it up. CA is the toughest market in the country, if you are a hybrid buyer; the deposit gets you a shot, so almost all buyers get stuck with it.
The "old figure" for AC use was that it took 5HP-a lot of power-probably enough to power the HCH ll at a steady 20-25 MPH.
The claim that you use less energy with the AC on than off might be correct for higher speeds especially with cars/SUVs with higher CDs. The HCH ll probably has a <.30 CD ,and Honda probably engineered it to remain clean with the window down. Don't they sell it in markets with colder weather-Canada,Europe etc , where folks don't use the AC or climate control year round?Heck, I wouldn't be surprised to find out that you can buy a Civic without an AC.
Well, 41 mpg is pretty decent. There is nothing wrong with your car, the problem is that Honda buyers are FE freaks, and the biggest freaks are right here.(I mean Freak in the best sense of the word).Luck,Charlie

 

FE of 41 in the first 1,000 miles is fine. Until the car breaks in, it won't go up much. Most say the big jump in mileage comes around 3,500 miles or so.

 

I decided to make the last two drives without air (something I can only do with my wife not in the car) and the rear windows partially cracked with the moonroof in popup-position. My FE actually climbed up almost 3 MPG. The I-MPG meters (is that what people call it?) stays almost constantly (even up slight hills and freeway overpasses) somewhere around what appers to be 55-60MPG and about 35MPG in the few miles of steeper hills and lights where I live. A few more gallons of this and I will probly be at my 45MPG mark where I want to be.

When I turn on the A/C, I do notice things happen: going up hill reduces my I-MPG feedback and my MPG average (drastically) and the I-MPG's hovers closer to 50 MPG or so but drastically decreases on even the slightest incline.

Anyway, if there's not too much traffic (exhaust) I'll start opening the windows.

Thanks,
Shawn

 

One of the tricks I found while driving an old wagon with a busted compressor (I was ditching it at the end of the year, and saw no point in fixing it) was that having both rear windows and the front passenger window open about two inches, and the driver's window closed, resulted in a nice breeze all the way around. It works in the HCH as well, though the effect isn't quite as pronounced. Good when the temps are under about 85, and you're moving at highway speeds.

 

Read your post and tried it today on the commute home. 61mpg!
Thanks for the tip!

 

Interesting thought. Having the drivers' window shut should mitigate the noise problem a bit, at least so long as you don't have any passengers

 

I have just over 650 miles on my HCH II and my average is about 36 mpg, I mostly drive with the AC on all the time. The HCH is rated at 50 mpg by the EPA and by what I see here this is definitely achievable, question is what do I do differently, shut off the AC all the time?

My wife has the has a 06 Prius and she manages an average of 45 mpg for the 1,650 miles that she has driven it with AC on all the time, while both these numbers are better that our previous cars these are well below what are advertised.

I have seen posts that reports 50 mpg on their first tank full for the HCH II, is there something wrong with my car?

 

Don't get hung up on MPG. You have some people here who have mastered the art. Read some of the advice if you want better MPG. The AC will steal MPG; running hard will too. The Prius and Civic you have both sound like you drive them hard with AC. Unless you are willing to change your driving habits, don't sweat it.

After 3,500 the mileage seems to increase. I was at 38 my first tank and have crept up to 41.7 average in harsh conditions with AC. Hills and other factors all weigh in.

What you should realize is that you are doing your part by driving 2 Hybrids. Even at "low" Fuel Efficiency, (FE), you are doing better than 99% of the drivers-and doing it twice over! On top of it-it's not just about using less fuel--it's also about lower emissions and you are doing it twice over.

So don't get hung up. Read the forums there is some great advice and you'll learn to better handle the car. I've never been near the EPA estimates in any car I own because of my driving habits and where I have to drive. i tend to drive a lot of short trips, with AC for 3-4 months, in cold in winter and on hilly, poorly designed highways (Long Island) plus I had a lead foot and still drive 68 in a 55.

There's nothing wrong with your car. Make sure your tire pressure is correct if you like and increase to maximum if you can handle the harsher ride, otherwise enjoy it and relax!

Best,

Michael